Example embodiments relate to a buck-boost conversion circuit, and more particularly, to a digital buck-boost conversion circuit for performing buck-boost conversion based on a digital control signal and a method of operating the same.
Recently, all electronic products are supplied with a constant voltage as an operating voltage. These electronic products include a voltage controller that supplies the constant voltage. A buck-boost converter is used as the voltage controller.
The buck-boost converter is a type of DC-to-DC converter that outputs a voltage neither higher nor lower than a reference voltage. The buck-boost converter functions as a boost converter that boosts an input voltage when the input voltage is lower than the reference voltage and functions as a buck converter that drops the input voltage when the input voltage is higher than the reference voltage.
Conventional buck-boost conversion circuits include a control circuit, which compare an output voltage of the buck-boost converter with the reference voltage and performs pulse width modulation (PWM) on a comparison result using a sawtooth signal to control the buck-boost converter.
Since conventional buck-boost conversion circuits operate in an analog mode, occupy a large area in a chip, and have low efficiency because they consume a large amount of current. Conventional buck-boost conversion circuits may cause electromagnetic interference (EMI), and a ripple component may occur in an output voltage of the conventional buck-boost conversion circuits.
Conventional buck-boost conversion circuits may be improved in terms of the area and current consumption, but research and development for removing EMI and ripple component is required. Accordingly, to remove EMI and ripple component, conventional buck-boost conversion circuits use a method of increasing or decreasing the frequency of PWM signal or a method of adding a noise component to a PWM signal. However, conventional buck-boost conversion circuits still cause high EMI and have a ripple component in their output voltages.